Signals running through fiber-optic cables deteriorate, and so the signals must be run through a piece of equipment called a regenerator before being transmitted farther.

通过光纤传输的信号会变弱，因此信号必须通过一种称为再生器的设备才能传输到更远的地方。

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If anyone can be called a scientific giant after Albert Einstein, that person must be Stephen Hawking.

如果有人能在爱因斯坦之后被称为科学巨人，那么这个人一定是史蒂芬·霍金。

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Rivers can differ in size and there is no strict rule on how big a flow of water must be to be called as a river.

河流的流域会有不同，对于有多大的流量才能被称为河流没有严格的规定。

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And he said in order to keep terrorist groups out of Afghanistan for the long term, the United States must help the country establish what he called "a more capable and accountable" government.

VOA: standard.2009.03.27

This is why he tells us parenthetically that marriage must not be called a defilement.

这就是为什么他顺便地告诉我们,婚姻不能被称为肮脏。

耶鲁公开课 - 弥尔顿课程节选

Edwards had called that primary a must-win contest.

CNN: Exit polls: Economy a chief concern

Called a continuing resolution, it must pass by March 27 to prevent a partial government shutdown.

CNN: Hope for compromise recedes as budget debate begins

But before a gene can make a protein, it must be transcribed onto a molecule called RNA. Researchers at Santa Clara, Calif.

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